Pneumatic hammer.



G. L. ROBERTSON.

PNEUMATIC HAMMER,

APPLICATION FILED APR. 9, 1913.

1,068,605, Patented July 29, 19-13.

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nnrrnn snares rarnnr GEORGE L. ROBERTSON, 0E PHILADELPHIA, PENN$YLVANIA,ASSIGNOR OF ONE-HALF T0 CHARLES MITCHELL, OF PHILADELPHIA, PENNSYLVANIA.

PNEUMATIC HAMMER.

Specification of Letters Patent.

Patented July 29, 1913.

Application filed April 9, 1913. Serial No. 759,850.

To all whom 2'25 may concern Be it known that I, Gnonon Lawson Roe-ERTSON, a citizen of the United States, residing at Philadelphia, in thecounty of Phila' delphia and State of Pennsylvania, have in ventedcertain new and useful Improvements in Pneumatic Hammers, of which thefollowing is a specification.

My invention relates to improvements in pneumatic hammers, the object ofthe invention being to provide improved means controlling the inlet ofpressure fluid to the hammer, so that accidental opening of the throttlevalve is prevented.

A further object is to provide an improved construction of throttlevalve with improved means for operating the same, which can only bemoved when a locking device has been previously operated to release thethrottle valve.

A further object is to provide in the handle of a pneumatic hammer, athrottle valve which is locked against movement by means of a levermovable by the hand in gripping the handle, and which throttle valve ismoved to open position by a second lever operated by the fingers of thehand as the latter grip the handle.

A further object is to provide improvements of this character which maybe utilized in connection with any ordinary hammer without addingmaterially to the cost of the hammer.

With these and other objects in view, the invention consists in certainnovel features of construction and combinations and arrangements ofparts as will be more fully hereinafter described and pointed out in theclaims.

In the accompanying drawings: Figure l is a fragmentary view inlongitudinal section illustrating my improvements, and Fig. 2 is a viewin elevation of the throttle valve removed.

1 represents a pneumatic hammer having a handle 2 in which a passage 3is provided for the pressure fiuid. The inlet end 4; of this passage 3is connected by a flexible pipe 5 with the source of fluid supply.Handle 2 is provided with an opening or bore 6 which intersects passage3, and in this opening or bore 6, a tube 7 is located and is providedwith openings 8 in opposite sides communicating with the passage 3, sothat the fluid has a flow transversely through the tube. One end of thistube 7 extends beyond the handle and is externally screwthreaded for thereception of a cap 9 effectually closing the tube. A throttle valve 10snugly fits within the tube 7, and has an annular groove 10 which whenmoved to register with the openings 8, permits a flow of fluid throughthe passage 3. This valve 10 is in the form of a piston, and whenclosed, cuts off the openings 8. The valve 10 is preferably integralwith an elongated stem 11 having a head 12 on its end against which acoiled spring 13 bears. The tension of this coileds'pring 13 isregulated by a set screw 14 screwed into the end of tube 7, and heldagainst accidental rotary movement by a spring-pressed pin 15 hearingagainst the serrated under face 16 of the head of said screw. The tube7, in opposite sides, is provided with longitudinal slots 17 and 18, andin line with these slots, the stem 11 is provided with openings 19 and20 respectively. A valve operating lever 21 is pivotally supported on apin 22 extending across a recess 23 in the handle. This lever 21 has afinger 24 which projects through the slot 17 and into the opening 19,and the free end of said lever 21 is formed with a transversely enlargedfinger hold 25 which when moved rearwardly, exerts a longitudinal pullon the stem 11 and valve 10 to move the valve to open position as willbe readily understood.

Spring 13 holds the valve in normal closed position and a shoulder 26 onlever 21 engages a shoulder 27 at the end of recess 23 to limit thepivotal movement of the lever 21.

In a recess 28 in handle 2, a locking lever 29 is located and ispivotally supported be tween its ends on a pin 30. At one end of thislever 29, a finger 31 is provided which projects through slot 18 intothe openin 20 and securely holds the stem 11 and valve 10 againstlongitudinal movement. A coiled spring 32 in the recess 28 exerts aconstant pressure on the lever 29 to hold the same in locked position,and said lever at its outer edge is enlarged transversely as shown at 33to fit the palm of the hand, so that a pres sure against the same willswing the lever on its pivot 30 and draw the finger 31 out of theopening 20. In operation, therefore, it

is necessary to first draw the finger 31 out of the opening 20 beforethe valve 10 can be moved, hence a pressure of the palm of the handagainst lever 33 must first be eflected before lever 21 is operated bythe fingers, to move the valve 10. The finger 31 therefore operates toprevent accidental movement of the throttle valve, and only throughdesign can the valve be opened because it is first necessary to operatethe lever 29 by pressure of the hand, and then operate the lever 21 bypressure of the fingers to move the valve.

Various slight changes might be made in the general form and arrangementof parts described Without departing from my invention, and hence I donot limit myself to the precise details set forth, but consider myselfat liberty to make such changes and alterations as fairly fall withinthe spirit and scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a pneumatic hammer, the combination with a handle having a fluidpassage therethrough, of a throttle valve, a stem on the throttle valve,a spring bearing against the end of the stem and normally holding thevalve in closed position, a locking lever pivoted between its ends andhaving one end engaging the stem normally holding the lat ter againstmovement, said last-mentioned lever projecting rea-rwardly beyond thesurface of the handle, the other of said levers pivoted at one end andhaving a finger grip at its free end, said last-mentioned lever betweenits ends engaging the said rod, substantially as described.

2. In a pneumatic hammer, the combination with a handle having a fluidpassage therethrough, a piston throttle valve controlling the flow offluid through said passage, a stem on said valve having two openingstherein, a locking lever pivotally supported between its ends in arecess in the handle, a finger on said lever normally projected into oneof the said openings, a valve operating lever pivotally supported in thehandle, and a finger on said last-mentioned lever projected into theother of said openings, substantially as described.

3. In a pneumatic hammer, the combination with a handle having a fluidpassage therethrough, of a tube secured in the ban dle and havingopenings at opposite sides registering with the fluid passage, a capscrewed onto one projecting end of said tube, a grooved throttle valvein said tube, a stem on the valve located in the tube and having twoopenings therein, a screw plug screwed into the end of said tube, aspring in said tube between the said plug and the stem normally holdingthe valve in closed position, a locking lever engaging in one of saidopenings in the stem, and a valve moving lever engaging in the otheropening of the stem, substantially as described.

at. In a pneumatic hammer, the combination with a handle having a fluidpassage theret-hrough, of a tube secured in the handle and havingopenings at opposite sides registering with the fluid passage, a capscrewed onto one projecting end of said tube, a grooved throttle valvein said tube, a stem on the valve located in the tube and having twoopenings therein, a screw plug screwed into the end of said tube, aspring in said tube between the said plug and the stem normally holdingthe valve in closed position, a spring-pressed locking lever in the rearportion of the handle, a finger on said locking lever projecting througha slot in the tube and into one of said openings in the stem, a valveoperating lever pivotally secured in a recess in the forward portion ofthe handle, a finger on said valve operating lever projected through aslot in the tube and into the other of said openings in the stem, andtransversely enlarged outer portions on both of said levers,substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

GEORGE L. ROBERTSON. Witnesses:

CrrAs. MITCHELL, CHAS. E. Porrs.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. G. i

